91 S10 Floods out at high RPM

    My 91 S10 is flooding out when it is at high RPM it idles fine and runs better when cold but still foods out a little.  I just changed an O2 sensor and when I took it out it was bad, very built up with carbon.  I looked it up in a HAYNES book and it said it could be a number of things.  Well I was told that since the O2 sensor was that bad it could be the converter cloging up. And someone else told me it could be the EGR valve.  What do you all think.  Thanks much.

some peaople tell me that the converter is cloged if the O2 sensor was that bad,  others say it might be the EGR valve